Lee Westwood faces a race against time to regain fitness for next week's Open at St Andrews after he was yesterday diagnosed with a slight tear in his right calf muscle.

The world number three hobbled through last week's French Open, but said at the end the problem had got progressively worse as the tournament went on and so withdrew from the JP McManus Pro-am in Ireland, which concludes today.

“He's been advised complete rest for the rest of the week, but is still very hopeful that everything will be fine,” said management spokesman Martin Hardy.

“He's been convinced that if everything pans out as expected he will be okay.”

The 37-year-old went to hospital last Wednesday for a check-up after an initial scare that he might be suffering from a blood clot or deep vein thrombosis, but further tests put his mind at rest on that.

Westwood had planned an early visit to St Andrews later this week, ahead of next Thursday's opening day, but that has now been cancelled.

Last July, he bogeyed the final hole to lose by a shot at Turnberry and this April he was runner-up in The Masters.